An internationally known UFO expert is suing to get his X-files back from a Staten Island woman who he says is greedily holding them for a $100,000 ransom.

Paranormal author and columnist Antonio Huneeus claims Esther Carroll reneged on an initial deal to sell him 160 boxes of his alien research and UFO photos for $6,000, according to a lawsuit filed June 5 in Staten Island Supreme Court.

“It’s all my personal belongings and research materials. She’s already made five times her investment.”

Carroll acquired the materials after Huneeus failed to pay his tab at Brooklyn Storage Mart, where he’d been housing the items for two years.

Carroll’s son bid $275 on the boxes when the storage facility auctioned them off on May 17.

The suit says Carroll agreed to part with the files – which range from declassified documents to a campy photo of Sen. Hillary Rodham Clinton holding an E.T.-like infant – for $6,000.

Huneeus wired Carroll $4,000, and said he would pay the other $2,000 once he inspected his belongings, the lawsuit says.

But after the first payment, she called off the deal and upped her asking price to an astronomical $100,000, he claims.

Carroll, 65, who lives off Social Security in a trailer park near the Goethals Bridge, told The Post she agreed to sell Huneeus only an oil painting, seven first-edition books, and clothes from his storage bin.

“I’ll be honest with you: I’m after the money,” said Carroll, who has held onto the $4,000 Huneeus gave her. “I don’t know about UFO stuff, neither do I want the stuff.”

Huneeus does know. The Chilean-born journalist said he once had a close encounter in the Andes when he saw lights flashing in the sky.